The invention relates to a method for setting the cut register in a web-fed rotary press and to an apparatus for implementing the method.
DE 199 36 291 A1 describes a method for determining the cut positions of part webs of a longitudinally cut printing material web in a web-fed rotary press, in which the part webs are combined into strands, folded in a former and finally cross-cut by a knife cylinder. In this case, the cut individual webs are designated part webs and the combined part webs after the former are designated strands. The cut positions determined are used to regulate the cut register, a dedicated control loop being provided for each part web and, in addition, an outer control loop being provided for the strand already folded. In this way, it is intended to make it possible to keep the cut positions of all the part webs of the folded strand at a desired value in each case.
Such regulation with a cascade structure is complicated and, in particular, requires the use of a large number of sensors for registering the actual values of the cut position on the individual part webs and on the folded strand. This is not only costly but, as the number of sensors used rises, the probability of failure of the cut register regulation also increases, since failures of automated systems are generally caused to a predominant extent by sensor failures.